No description
  • C 98.2%
  • Assembly 1%
  • Makefile 0.3%
  • Shell 0.2%
  • Python 0.1%
Find a file
Repository files (latest commit first)
Filename Latest commit message Latest commit date
Marco Elver 84255fe86d debugobjects: Fix various data races
[ Upstream commit 35fd7a637c42bb54ba4608f4d40ae6e55fc88781 ]

The counters obj_pool_free, and obj_nr_tofree, and the flag obj_freeing are
read locklessly outside the pool_lock critical sections. If read with plain
accesses, this would result in data races.

This is addressed as follows:

 * reads outside critical sections become READ_ONCE()s (pairing with
   WRITE_ONCE()s added);

 * writes become WRITE_ONCE()s (pairing with READ_ONCE()s added); since
   writes happen inside critical sections, only the write and not the read
   of RMWs needs to be atomic, thus WRITE_ONCE(var, var +/- X) is
   sufficient.

The data races were reported by KCSAN:

  BUG: KCSAN: data-race in __free_object / fill_pool

  write to 0xffffffff8beb04f8 of 4 bytes by interrupt on cpu 1:
   __free_object+0x1ee/0x8e0 lib/debugobjects.c:404
   __debug_check_no_obj_freed+0x199/0x330 lib/debugobjects.c:969
   debug_check_no_obj_freed+0x3c/0x44 lib/debugobjects.c:994
   slab_free_hook mm/slub.c:1422 [inline]

  read to 0xffffffff8beb04f8 of 4 bytes by task 1 on cpu 2:
   fill_pool+0x3d/0x520 lib/debugobjects.c:135
   __debug_object_init+0x3c/0x810 lib/debugobjects.c:536
   debug_object_init lib/debugobjects.c:591 [inline]
   debug_object_activate+0x228/0x320 lib/debugobjects.c:677
   debug_rcu_head_queue kernel/rcu/rcu.h:176 [inline]

  BUG: KCSAN: data-race in __debug_object_init / fill_pool

  read to 0xffffffff8beb04f8 of 4 bytes by task 10 on cpu 6:
   fill_pool+0x3d/0x520 lib/debugobjects.c:135
   __debug_object_init+0x3c/0x810 lib/debugobjects.c:536
   debug_object_init_on_stack+0x39/0x50 lib/debugobjects.c:606
   init_timer_on_stack_key kernel/time/timer.c:742 [inline]

  write to 0xffffffff8beb04f8 of 4 bytes by task 1 on cpu 3:
   alloc_object lib/debugobjects.c:258 [inline]
   __debug_object_init+0x717/0x810 lib/debugobjects.c:544
   debug_object_init lib/debugobjects.c:591 [inline]
   debug_object_activate+0x228/0x320 lib/debugobjects.c:677
   debug_rcu_head_queue kernel/rcu/rcu.h:176 [inline]

  BUG: KCSAN: data-race in free_obj_work / free_object

  read to 0xffffffff9140c190 of 4 bytes by task 10 on cpu 6:
   free_object+0x4b/0xd0 lib/debugobjects.c:426
   debug_object_free+0x190/0x210 lib/debugobjects.c:824
   destroy_timer_on_stack kernel/time/timer.c:749 [inline]

  write to 0xffffffff9140c190 of 4 bytes by task 93 on cpu 1:
   free_obj_work+0x24f/0x480 lib/debugobjects.c:313
   process_one_work+0x454/0x8d0 kernel/workqueue.c:2264
   worker_thread+0x9a/0x780 kernel/workqueue.c:2410

Reported-by: Qian Cai <cai@lca.pw>
Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20200116185529.11026-1-elver@google.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
2020-02-24 08:36:52 +01:00
arch perf/x86/amd: Constrain Large Increment per Cycle events 2020-02-24 08:36:52 +01:00
block block, bfq: do not plug I/O for bfq_queues with no proc refs 2020-02-24 08:36:31 +01:00
certs
crypto crypto: essiv - fix AEAD capitalization and preposition use in help text 2020-02-24 08:36:50 +01:00
Documentation fbdev: fix numbering of fbcon options 2020-02-24 08:36:42 +01:00
drivers EDAC/sifive: Fix return value check in ecc_register() 2020-02-24 08:36:51 +01:00
fs f2fs: free sysfs kobject 2020-02-24 08:36:50 +01:00
include raid6/test: fix a compilation warning 2020-02-24 08:36:47 +01:00
init
ipc ipc/msg.c: consolidate all xxxctl_down() functions 2020-02-11 04:35:07 -08:00
kernel watchdog/softlockup: Enforce that timestamp is valid on boot 2020-02-24 08:36:52 +01:00
lib debugobjects: Fix various data races 2020-02-24 08:36:52 +01:00
LICENSES
mm mm/mmu_gather: invalidate TLB correctly on batch allocation failure and flush 2020-02-11 04:35:42 -08:00
net bpf: Return -EBADRQC for invalid map type in __bpf_tx_xdp_map 2020-02-24 08:36:48 +01:00
samples samples/bpf: Set -fno-stack-protector when building BPF programs 2020-02-24 08:36:36 +01:00
scripts kbuild: remove *.tmp file when filechk fails 2020-02-24 08:36:49 +01:00
security selinux: ensure we cleanup the internal AVC counters on error in avc_update() 2020-02-24 08:36:39 +01:00
sound ALSA: usb-audio: add implicit fb quirk for MOTU M Series 2020-02-24 08:36:50 +01:00
tools usbip: Fix unsafe unaligned pointer usage 2020-02-24 08:36:44 +01:00
usr
virt KVM: arm64: Treat emulated TVAL TimerValue as a signed 32-bit integer 2020-02-14 16:34:18 -05:00
.clang-format
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore
.mailmap
COPYING
CREDITS
Kbuild
Kconfig
MAINTAINERS MAINTAINERS: correct entries for ISDN/mISDN section 2020-02-11 04:35:06 -08:00
Makefile Linux 5.4.21 2020-02-19 19:53:10 +01:00
README

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.